1. Field of the Invention
The present invention is directed to a stray radiation grid, particularly for a medical X-ray apparatus of the type composed of a carrier material with absorption elements, particularly in the form of lead lamellae, that are arranged in rows spaced from one another and proceeding essentially parallel to one another, whereby the spacing between the rows of absorption elements is larger in the region of the edges of the grid than in the middle region.
2. Description of the Prior Art
Stray radiation grids are employed in X-ray diagnostics for the suppression of stray radiation. The effectiveness of such a grid is particularly characterized by the line density (in lines per centimeter) and by its geometry, i.e. the ratio of height and thickness of the intermediate medium. This ratio is called the shaft ratio. In order to avoid a higher occlusion by the absorption elements, i.e., for example, the lead lamellae, in the outside regions than in the center, the grids are fashioned such that the absorption elements are aligned to the focus of the radiator, i.e. are "focussed". The focus spacing is thus a characteristic quantity of such grids. In these known grids, thus, the lead lamellae are arranged tilted. Alternatively, it is also known to conically erode the finished grid at one side, proceeding from the middle, and thus to modify the geometry. The known grids are composed of a carrier usually composed of paper; the absorption elements are usually lead lamellae. A disadvantage of the known embodiments is, for the first version described above, the manufacture thereof, since the lead lamellae arranged focussed, i.e. residing obliquely, must be brought into this focussing alignment in a complicated and extremely precise way. In the case of the slanted grid, the post-processing during manufacture is extremely involved.
A stray radiation grid of the above-described type is described in U.S. Pat. No. 4,951,305. Given this grid, the spacing of the absorption elements of the respective grid or plane varies such that it is smaller in the middle of the grid than at the edge regions. A disadvantage, however, is that the grid exhibits a different absorption behavior over its area or surface caused by the increasing spacing of the absorption elements.